Tube bank headbox

ABSTRACT

A HEADBOX CONSTRUCTION FOR A PAPERMAKING MACHINE WHEREIN THE HEADBOX FORMS A HOUSING HAVING A RECEIVING CHAMBER AND AN EXIT CHAMBER AND A PLURALITY OF TUBES OR PIPES CONNECTED BETWEEN THE CHAMBERS TO DIRECT STOCK FLOW TO THE EXIT CHAMBER WHEREUPON THE STOCK IS DELIVERED TO A FORMING SURFACE. THE TUBES HAVE ONE END THEREOF SECURED TO A PERFORATED PLATE WHICH, IN TURN, FORMS AT LEAST A WALL PORTION OF THE RECEIVING CHAMBER, AND THE OTHER END OF THE TUBES IS SECURED TO A SECOND PERFORATED PLATE, WHICH IN TURN, FORMS AT LEAST A WALL PORTION OF THE EXIT CHAMBER. ALSO, THE TUBES, HEREINAFTER REFERRED TO AS A TUBE BANK, ARE BENT IN SUCH A MANNER AS TO CHANGE THE DIRECTIONAL FLOW OF THE STOCK.

Feb. 9, 1971 J. Ff-f'scHMAl-:NG 3,552,107

' TUBE BANK HEADBox Filed Aug. 29, 1967 3 Sheets-Sheet l l N VENT( )R @n INVENTOR L: BY

- fE um LJZZZZ j'ldzfzzazzzg o l @mrd-M Ys Feb. 9, 1971 J. F. scHMAENG TUBE BANK HEADBOX 5 Sheets-Sheet 3 Filed Aug. 29, 1967 ill aw, Mw.

United States Patent O T 3,562,107 TUBE BANK HEADBOX `lohn F. Schmaeng, Rockton, Ill., assignor to Beloit Corporation, Beloit, Wis., a corporation of Wisconsin Filed Aug. 29, 1967, Ser. No. 664,153 Int. Cl. D21f 1/02 U.S. Cl. 162--336 1 Claim ABSTRACT OF THE DISCLOSURE A headbox construction for a papermaking machine wherein the headbox forms a housing having a receiving chamber and an exit chamber and a plurality of tubes or pipes connected between the chambers to direct stock ow 4to the exit chamber whereupon the stock is delivered to a forming surface. The tubes have one end thereof secured to a perforated plate which, in turn, forms at least a wall portion of the receiving chamber, and the other end of the tubes is secured to a second perforated plate, Which in turn, forms at least a wall portion of the exit chamber. Also, the tubes, hereinafter referred to as a tube bank, are bent in such a manner as to change the directional flow of the stock.

BACKGROUND OF THE INVENTION Field of the invention This invention relates generally to a headbox for a papermaking machine, and more particularly to a headbox construction which includes a plurality of passages formed by a tube bank to direct or channel stock ow toward the slice opening of the headbox in a uniform manner.

Description of the prior art Heretofore, attempts to establish the uniform distribution of the bers in the stock slurry and to maintain a ber distribution, once established, along the flow path in the headbox prior to distribution of the slurry on the forming surface of a papermaking machine, have involved employment of such complicated auxiliary equipment as perforated rotary rolls, commonly referred to as rectifier rolls, holly rolls, or the slicing rolls, and other mechanical vibrating shaking and stirring devices, all of which induce turbulent flow of large scale amplitude in the slurry.

Additionally, some headboxes of the prior art have incorporated aperture plates, rod banks, and other forms of abutments in the stock flow in an attempt to obtain the desired stock flow characteristic. However, in such headbox constructions, the abutments are placed at various positions throughout the headbox such that the stock flows through the headbox as a continuous liquid mass, in the cross stock ow direction, lbefore impinging upon the abutments, and immediately after passing the abutment the stock will coalesce once again to form a coritinuous liquid mass, in the cross stock flow direction.

A major disadvantage of such headbox constructions of the prior art reside in the affinity of the fibers in the large scale turbulent flow of the slurry to form clots, flocs, and agglomerations which, when deposited on a forming surface result in undesirable localized irregularities of high intensity in the formed mat. In some instances, such clots and the like cause breakdown of the mat, thereby interrupting production.

SUMMARY OF THE INVENTION By utilizing a headbox construction according -to the present invention, we have eliminated the requirement for rotary, vibratory or other moving auxiliary means heretofore employed. Additionally, the headbox construc- 3,562,107 Patented Feb. 9, 1971 ICC tion of the present invention, although not eliminating perforated plates, and abutments, have utilized such elements together with a tube rod bank in a unique and novel combination to obtain the desired stock ow through the slice opening of a headbox. That is, the unique and novel combination of elements of the present invention provide for delivery of the stock slurry to a forming surface of a papermaking machine under conditions of substantially uniform mean velocity, minimum large scale flow turbulence, and minimum gross stationary flow patterns wherein the ber distribution and dispersion in the liquid vehicle are substantially uniform thereby permitting formation on the forming surface of a mat having substantially uniform intensity and ber distribution throughout. The practice of the present invention also substantially reduces the formation of the undesirable clots, flocs or agglomerations in the stock flow.

Accordingly, it is an object of the present invention to provide improved methods and means for establishing and maintaining particles of substantially uniform means distribution in a flowing liquid medium and to substantially reduce formation of undesirable clots, ocs and agglomerations in the stock slurry at the slice of a papermaking machine.

Another object of the present invention is to control the condiiton of ow of the stock slurry immediately prior to its delivery to the forming surface of a papermaking machine.

It is a further object of the present invention to eliminate the requirements for rotary, vibratory, or other moving auxiliary means in the headbox of papermaking machines by providing for delivery of the stock slurry to the forming surface of a papermaking machine under conditions of substantially uniform mean velocity, minimum vide apparatus for controlling the distribution of the bers in a slurry for papermaking processes which is simple, compact in construction, eicient, and suitable for high speed papermaking applications.

A feature of the headbox of the present invention is the provision of a tube bank disposed within the headbox between a receiving chamber and an exit chamber.

Another feature of the present invention is the utilization of an adjustable wall portion of the exit chamber to control the slice opening.

Still another feature of the present invention is in the provision of means for pivotably mounting the headbox and adjusting means on the headbox so as to adjust the position of the headbox about the pivotable mounting, thereby adjust the position of the slice opening relative to a forming surface.

Still another feature of the present invention is the provision of a headbox construction which is suitable for use with a two-wire forming surface.

These and other objects and features will be more fully realized and understood from the following detailed description when taken in conjunction with the accompanying drawings in which like reference numerals throughout the various views of the drawings are intended to designate similar elements or components.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross sectional elevational view showing a headbox construction and mounting in accordance with the principles of this invention;

FIG. 2 is an enlarged fragmentary view showing the construction of the tube bank shown in FIG. l;

FIG. 3 is an enlarged sectional view taken along the lines III-III of FIG.

FIG. 4 is an enlarged sectional view taken along the lines IV-IV of FIG. 6;

FIG. 5 is an elevational plan view taken along the lines V-V of FIG. 2 showing the inlet plate of the tube bank of FIGS. 1 and 2; and

FIG. 6 is an elevational plan view taken along the lines VI-VI of FIG. 2 showing an exit plate of the tube bank of FIGS. 1 and 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As seen in FIG. 1, a headbox l10 is provided with a top cover 11 which is secured to a main body 12. Also secured to the main body 12 is a bottom or tloor portion 13. A flange 14 is pivotably mounted to a clevis bracket 16 by a pivot pin 17. The clevis bracket 16 is secured to an I-beami18 which, in turn, is supported by a standard 19.

Also secured to the headbox 10 is a flange 20 which is connected to a clevis bracket 21 via an extensible portion 22 of a jack 23. The clevis bracket 21 is secured to an I-beam 24 which, in turn, is supported by a standard 26. 'I'he pivot pin 17 and the jack 23 serve to provide means for adjusting the position 0f the headbox on the standards 19 and 26.

The standards 19 and 26 may extend to baseplates or be supported off the bottom wire frame beam 27. A breast roll 28 may be provided when the headbox 10 is used as the primary headbox. The breast roll 28 is wrapped by a wire 29 which, in turn, forms a forming surface for the mat or web. A second roll 30 may be positioned above the breast roll Z8. The second roll 30 carries a web 31 which together with lthe web 29 come together to form a paper web therebetween. In some instances, it may be desirable to adjust the position of the roll 30 relative to the roll 28 so as to control the properties of the paper web formed therebetween.

The headbox 10' is provided with a slice opening 32 which extends toward the nip region between the rolls 28 and 30. As mentioned hereinabove, the pivot pin \17 and the jack 23 provide means for adjusting the position of the headbox on the standards 19 and 26. Therefore, the slice opening 32 can be adjusted to the desired position between the rolls 28 and 30.

In the headboxes of the prior art, conventional type knife-edge adjusting means have been provided, however, the novel headbox construction of the present invention utilizes a movable wall portion 33 which forms a part of a receiving chamber 34. The movable wall portion 33 is a prefabricated structure including a slanted wall portion 36 which conforms to a corresponding slanted wall portion of the headbox 10. The slanted wall portion 35 makes an angle A of 56 with an adjacent wall portion 37, of the receiving chamber 34. A seal 38 is positioned between the slanted wall portions 35 and 36. The seal 38 is of tluorocarbon material such as Teon and acts as a slide bearing surface.

An apertured exit plate 39 forms a wall portion of the exit chamber 34 and is connected to an apertured receiving plate -40 via a plurality of tubes 41. The structure including the plates 39 and 40 and the tubes 41 form a tube bank. The construction of the tube bank is such that the forward row of tubes connected to the receiving plate 40 extend downwardly a short distance and then angle toward the second row of tubes and come in alignment therewith prior to making a radius 41a. Similarly, the third row of tubes extend downwardly and then angle toward the back row of tubes so as to come in alignment therewith prior to make a radius 41b. Therefore, four ro'ws of tubes extending in the cross machine direction emerge as two rows of tubes extending in the cross machine direction at the exit plate 39.

The receiving plate 40 forms a wall portion of a receiving chamber 42. Also forming a Wall portion of the receiving chamber 42 is a distribution plate assembly 43 which has a plurality of apertures 44. Connected to the backside of the distribution plate assembly 43 is a manifold 46 which may be chambered in the cross machine direction so as to provide a uniform pressure gradient in the cross machine direction to uniformly supply stock through each of Ithe apertures 44. A level control 4 may be incorpoarted in the receiving chamber 42.

To adjust the slice opening 32, the wall portion 33 may be moved by adjusting a jack 48 which has its extensible element 49 connected to a boss 50 on the headbox 10. By adjusting the position of the jack 48, the wall portion 33 will move upwardly, as the wall portion 36 slides along the Teflon seal 38.

A resilient member 51 forms a portion of the wall 33 and has the outward-most edge thereof connected to a link 52 through .a boss member 53. The link 52 is pivotably secured by a pin 54 which engages the exterior portion of the wall 33. As the turnbuckle 56 is adjusted, the link 52 pivotably rotates about the pin 54 so as to flux the resilient member 51 thereby opening or closing the slice opening 32. Assemblies comprising links 52, boss 53, pin 54 and turnbuckle 56 are provided along the slice in the cross machine direction at intervals of approximately six inches to form individual adjusters so that the stock prole may be adjusted as desired.

The detailed construction of the tube bank of the present invention is best seen in FIGS. 2, 3, 4, 5 and 6. Also, as best seen in FIG. 2, a pair of hump plates 57 are positioned in the exit chamber 34 and serve to induce controlled turbulence into the stock as the stock travels between the exit plate 39 and the slice opening 32. However, since the stock travels a relatively short distance, as compared to prior art headboxes, between the exit plate 39 and the slice opening 32, the hump plates 57 may be relatively small, and in some cases completely eliminated.

As seen in FIG. 3, one end surface of the receiving plate 40 is angled at an angle B which, is preferably 27 to conform substantially with the mating Wall portion of the receiving chamber 42. Also, the apertures 40a of the plate 40 preferably have the same diameter as the inside diameter of the tubes 41. Another method securing the tubes 41 to the plate 40 is to extend the tubes through the plate and roll the tubes in position and thereafter nish and polish the entrance surface.

As seen in FIG. 4, one end surface of the plate 39 makes an angle C to conform with the inside surface of the wall portion 37. The extended tapered opposed wall portions of the exit chamber 34 converge in the slice direction at an angle D, which is preferably 4. Each of the apertures 39a form a diffuser nozzle to discharge the stock into the chamber 34. In the preferred embodiment, the included angle E of each of the diluser nozzles is less than 25.

FIG. 5 shows the detail of the apertures 40a of the plate 40. The apertures 40a are positioned in four staggered rows in the cross machine direction such that the center line of each aperture in each row is displaced from the center line of each aperture in each adjacent row so that a land dimension of not less than one inch is provided. This prevents stapling of ber bundles or strings from sticking to the land area. As seen in FIG. 6, the apertures 39a of the plate 39 are positioned in two rows in the cross machine direction, and the center of each aperture in one row is displaced from the center of each aperture in the adjacent row. It has been found that the most desirable hole pattern is one which forms a 60 angle :between the centers of the apertures 39a, as indicated by reference letter F. The 60 hole pattern may vary i5 to provide a suitable stock flow pattern for a particular machine width.

Accordingly, the headbox of the present invention provides new and novel means for delivering stock to a slice opening and which stock is relatively free of clots, ilOCS and agglomerations. The tube bank within the headbox serves to channel the stock ow through the headbox in such a manner as to reduce large scale turbulence within the stock ow and to generate small scale turbulence. Also, the tube bank within the headbox provides a greater surface area in contact with the stock flow to afford a greater shearing effect on the stock in the vicinity of the inner walls of the tubes, such shearing effect also generates small scale turbulence in the stock as the stock is delivered to the exit chamber 34.

Furthermore, the tube banks may be of rigid tube design with attached distributor and air cushion. An alternate arrangement would be to have flexible tubes from a hydraulic header cantilevered across the forming wire. The flexible tubes would permit maximum flexibility of the nozzle, or discharge chamber 34, relative to the forming nip. Another alternate arrangement would be to have the flexible tubes originate at a surge tank and then radiate to a movable nozzle.

An improved feature of the present invention is obtained by the wide lands one inch or more, on the upstream apertured plate 40 which serve to prevent stapling of liber and fiber bundles. Relatively small tubes dampen large scale disturbances while the drag on the tube walls generate small scale turbulence of high intensity which thoroughly dissipate the fibers in the stock. Also, the approach of each of the tubes 40 toward the apertured plate 39 as made collinear with that of the diffuser holes 39a so as to provide a unidirectional stock flow path into the nozzle chamber 34. The tubes may be collinear with the diffuser holes for an axial extent of approximately six inches.

Additionally, the tubes afford means to direct the stock around corners in a precise direction without generating large scale secondary flows or cross currents.

The exit ends of the tubes, including the apertures 39a diverge in such a manner as to minimize the land area between the apertures on the down stream surface there by preventing large scale disturbances from being generated by merging jet streams from the individual tubes.

6 It will *be noted that maximum open area of the exit plate 39 is desirable.

Accordingly, it will be understood that other variations and modifications may be effected without departing from the spirit and scope of the novel concepts of this invention.

I claim as my invention:

1. A headbox for a papermaking machine comprising a headbox housing,

means including first and second perforated plates disposed substantially at right angles to one another for forming in said headbox a chamber for receiving stock and an exit chamber for delivering the stock to a slice opening,

a plurality of tubes interconnecting the perforations of said plates,

the perforations in said second plate being frustoconically shaped and diverging from one end which is adjacent said tubes and which is equal in diameter to the inside diameter of said tubes to an opposite end facing the slice opening,

the angle of divergence of said perforations being in the order of about 25, and

means forming a plurality of hump plates in said exit chamber as the only obstructions in said exit chamber between said second perforated plate and the slice opening and located immediately downstream of said second perforated plate.

References Cited UNITED STATES PATENTS 3,215,593 ll/l965 Green l62-344X 3,445,331 5/1969 Lee et al. 162-336X 3,309,264 3/1967 Parker et al. 162-343X 3,328,236 6/1967 Burgess, Jr. et al. l62-343X 3,400,044 9/1968 Justus l62-339X REUBEN FRIEDMAN, Primary Examiner T. A. GRANGER, Assistant Examiner 

